title: Dead space mask eliminates central apnea at altitude.
abstract: Travelers to high altitude may have disturbed sleep due to periodic breathing with frequent central apneas. We tested whether a mask with added dead space could reduce the central apneas of altitude. 16 subjects were recruited, age 18-35, residing at 4600 ft (1400 m). They each slept one night with full polysomnographic monitoring, including end tidal CO2, in a normobaric hypoxia tent simulating 12,000 ft. (3658 m) altitude. Those who had a central apnea index (CAI) >20/h returned for a night in the tent for dead space titration, during which they slept with increasing amounts of dead space, aiming for a CAI <5/h or <10% of baseline. Then each subject slept another night with the titrated amount of dead space. Of the 16 subjects, 5 had a central apnea index >20/h mean 49.1, range 21.4-131.5/hr. In each of the 5, the dead space mask reduced the CAI by at least 88% to a mean of 3.1, range 0.9-7.1/h, (p=0.04). Hypopnea index was unchanged. Three subjects required 500 cc of dead space or less. One subject required 860 cc, and one required 2.1 L. Morning symptoms and arousal index were not significantly affected by the dead space mask. Dead space did not appear to increase the CO2 reserve. At 12,000 ft., central apneas can be effectively reduced with a dead space mask, but clinical utility will require further evaluation.
authors.affiliation: St. Mary's Hospital, Grand Junction, CO 81507, USA. davidsamuelpatz@hotmail.com
authors.forename: David S
authors.initials: DS
authors.lastname: Patz
authors.forename: Michael D
authors.initials: MD
authors.lastname: Patz
authors.forename: Peter H
authors.initials: PH
authors.lastname: Hackett
mesh_terms: D000293:Adolescent; D000328:Adult; D000399:Air Pressure; D000531:Altitude; D000532:Altitude Sickness / Q000503:physiopathology / Q000628:therapy*; D004867:Equipment Design; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008397:Masks; D017286:Polysomnography; D012126:Respiratory Dead Space; D020182:Sleep Apnea, Central / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome; D055815:Young Adult